The present invention relates to a machining apparatus and a machining method of machining an end face of a work, a roller provided by the machining method, and a roller bearing having the roller.
An end face of a work of a roller bearing slides on a rib on a side of a track ring and therefore, in order to reduce friction heat generated between the end face of the roller and the rib, as shown by FIG. 13 and FIG. 14, a crowned face 2 is provided between an end face of a roller 1 and an outer diameter face of a roller 1.
As a method of machining such a crowned face 2 at the end face of the roller 1, there is known a method of machining the end face of the roller by an elastic grinding wheel having Young's modulus of 10 MPa through 500 MPa by using a horizontal type double head surface grinder.
According to the method of machining an end face of a roller, the rollers are not machined piece by piece but the rollers can be machined at a high efficiency by continuous machining. Further, the roller can be machined smoothly without producing an edge at a portion of connecting the outer diameter face and a chamfer face 3, a portion of connecting the chamfer face 3 and the crowned face 2, and a portion of connecting the crowned face 2 and a plane portion of the end face of the roller (refer to, for example, Patent Reference 1).
In addition, there is provided a method of machining an face of a roller which allows the machining of an end face of a work while rotating the work and the machining of the end face of the roller at a high efficiency (refer to, for example, Patent References 2 and 3)
[Patent Reference 1]
Unexamined Japanese Patent Application Publication No. 2003-21145
[Patent Reference 2]
DE No. 2636689
[Patent Reference 3]
Japanese Patent No. 3455411
However, although according to Patent Reference 1, mentioned above, a smoothly continuous crowned shape can be continuously machined at the end face of the roller with a high efficiency, there is a drawback that accuracy of roller end face runout with outside surface is poor since rotation (self rotation) of the work is not stabilized.
On the other hand, according to Patent References 2 and 3, mentioned above, accuracy of swinging the end face of the roller can be improved since the end face of a work is machined while rotating the work. However, there is a drawback that shape differences in the end face of rollers after machining will be larger if such differences exist before machining since a machining tool is pressed to the end face of the work at a fixed position.